1. Field of the Invention
The present invention relates to a system for treating a workpiece (such as a continuous steel rod) by applying a liquid to the workpiece and by heating the workpiece such that the liquid is dried by residual heat.
The present invention also relates to a system for conditioning liquid (such as a borax solution) by removing contaminants from the liquid.
2. Description of the Related Art
It is known to provide an acid pickled rod with an inorganic lubricant carrier coating prior to size reduction by drawing. The purpose of the inorganic coating is to reduce direct contact between the rod and the drawing die, and to thereby reduce die wear and metal pickup.
With the increased emphasis on pollution control, acid pickling is being replaced by a non-polluting process called mechanical descaling. Mechanical descaling is advantageous because its only by-product is brittle scale that is relatively easy to dispose of, in contrast to the voluminous spent acid that is the by-product of acid pickling.
Bare mechanically descaled steel rod cannot be drawn with the same productivity as acid pickled rod coated with an inorganic coating, even when the same lubricating system is used. Therefore, it has been suggested to provide mechanically descaled rod with an inorganic coating after descaling to simulate the traditional practice. However, attempts at treating mechanically descaled rod in this manner have not been satisfactory.
The problem is that there has been no satisfactory system for drying the mechanically descaled rod subsequent to coating liquid application. Mechanical descaling does not significantly raise the temperature of the rod being descaled. Therefore, coating liquid applied to the rod will not dry by itself. Mechanically removing a portion of the coating liquid allows the rod to dry faster, but also significantly reduces the thickness of the coating left on the rod. Drying may also be accomplished by passing the rod up to twenty times around a drying drum, through a heated tube or through a hot air dryer. But when the coating liquid is transferred to drying drums or sheaves it becomes sticky and non-uniform. The result is a thin, non-uniform coating that cannot perform with the desired effectiveness during drawing, and that cannot provide adequate protection after drawing.